Gas detection using quenching fluorescence of dye-immobilised silica nanoparticles

A novel oxygen (O-2) and sulphur dioxide (SO2) gas sensor was produced by incorporating fluorophores within silica nanoparticles (SiNPs). The fluorophore rhodamine B isothiocyanate (RBITC) was encapsulated within SiNPs (208 +/- 9 nm) to produce a nanosensor that is sensitive to SO2, while ruthenium-tris(4,7-diphenyl-1,10-phenanthroline) dichloride (Ru(dpp)(3)) was encapsulated within silica nanoparticles (192 +/- 8 nm) to sense O-2. The sensor utilises the fluorescence quenching phenomena as a detection mechanism. Core-shell SiNPs were immobilised in organically modified sol-gel (ormosil) composed of octyltriethoxysilane (OTEOS) and methyltriethoxysilane (MTEOS). The surfaces of SiNPs were modified with carboxylic acid groups in order to bind the SiNPs within the ormosil matrix. A film was produced where Ru(dpp)(3) encapsulated silica nanoparticles were combined with RBITC encapsulated silica nanoparticles within a sol-gel matrix. The fluorescence of Ru(dpp)(3) was highly quenched by O-2 whilst RBITC was highly quenchable by SO2. Furthermore, the nanosensor was capable of detecting oxygen levels as low as 0.018% and SO2 gas at 50%. These novel nanosensors demonstrate potential to develop multisensor systems capable of detecting multiple gasses simultaneously in a single matrix for a magnitude of future applications that require small robust gas sensing. (c) 2013 Elsevier B.V. All rights reserved.